TEM investigation of self-organized PbSe quantum dots as a function of spacer layer thickness and growth temperature

PbSe quantum dot/PbEuTe superlattices were grown on PbTe/BaF2(111) using molecular beam epitaxy. The spacer thickness was varied from 32.4 to 312 nm and the growth temperature was 335 or 380°C. Three different dot stacking sequences form with either vertical, face-centered cubic like or disordered stacking sequence along the [111] growth direction. The different stacking sequence can be controlled by the thickness of the spacer layer and the growth temperature. The dots are fully strained and the shape of the dots is either triangular pyramids or dome like depending on the spacer layer thickness. An analysis of the lateral and vertical correlation of the dots as well as the size and shape of the buried dots with respect to spacer thickness and growth temperature is presented.